1. Field of the Invention
The present invention relates generally to the field of automated systems for handling samples in a laboratory environment and, more specifically, to systems for transporting, storing and retrieving large numbers of microplates used in applications such as high throughput screening.
2. Background Information
Industrial concerns, regulatory agencies and academic centers which conduct high throughput screening (HTS) or similar applications are faced with a problem of how to store, retrieve and transport hundreds or thousands of microplates which are necessary for such screening. While it may be generally desirable to automate these tasks as much as possible, there are numerous factors which must be taken into account for any automation effort to be successful. Human safety, system reliability, security, environmental control, and space requirements are but a few of the more important factors.
Another important aspect in designing automated systems for HTS is the ease with which one piece of equipment interfaces with another. Appropriate interfaces are necessary to avoid costly bottlenecks or delays while maintaining appropriate environmental conditions with respect to samples. In addition, it may be necessary to provide interfaces between equipment made by different manufacturers in order to accommodate the requirements of a customer""s application.
In brief summary, the present invention provides a collection of components for storing, retrieving and transporting large numbers of microplates in a highly integrated and automated system. The components readily interface with each other, thus enabling a high volume of microplates to be passed among the components for desired processing or storage. In addition, one component, a microplate transport, provides a way to transport microplates to or from third party equipment which a customer may wish to use in conjunction with the present invention""s components.
In accordance with one aspect of the present invention a random access storage and retrieval system for storing on the order of one thousand microplates in a very compact, highly efficient manner is provided. In a preferred embodiment, the storage and retrieval system includes a series of rectangular metal racks, each capable of storing up to 36 microplates. The racks are stacked upon one another. Each corner of each rack is mechanically engaged with a support column by way of a tongue and groove arrangement which allows the rack to be selectively locked to the four support columns by way of pneumatic pistons.
After a particular rack is locked to the support columns, a hydraulic lift raises the support columns a short distance, effectively creating a clearance immediately below the locked rack. Using an elevator attached to one side of the racks, a robotic crawler is lifted until it is approximately level with the rack below the clearance. By using a rack and pinion to move across the storage rack, the crawler is able to effectively access the entire area of the rack and either store or retrieve one or more microplates.
Once the robot has completed its operations on a particular rack, the robot is withdrawn into the elevator and lowered to its base. The hydraulic lift then lowers the support columns to their resting position and the pneumatic pistons are depressurized, thus unlocking the rack that was previously locked. A microprocessor-based controller controls the operations of the hydraulic lift, pneumatic pistons, elevator and robot.
In a second aspect of the invention, a microplate transport for moving microplates between one workstation and another is provided. In a preferred embodiment, the transport includes a carriage which is driven along a pair of rails by a servo. The carriage is capable of carrying two microplates on a turntable. Driven by a second servo, the turntable may be turned to allow a microplate to be placed in or removed from either of two holders. Sensors, located beneath and at opposite ends of the rails, work in conjunction with the servos and a controller to stop the carriage at the correct position and to turn the turntable to the correct angular position for loading or unloading the microplates.
The microplate transport is operable in accordance with any of several methods to perform different tasks. In a first method, the transport is used to move microplates from one location, referred to as the home location, to another location, referred to as the away location, for processing and, subsequently, to return the processed microplates to the home location. This method begins with the loading of the carriage with a single microplate at the home location. The carriage is driven to the away location, and the microplate is removed for processing. The carriage returns to the home location and is loaded with another microplate. The carriage is driven again to the away location and arrives with its microplate in the inboard side and an open slot in the outboard side. A microplate that was previously left for processing at the away location is now loaded into the outboard side. The turntable is turned 180xc2x0 and the microplate that was last loaded at the home location is removed. The carriage then returns to the home location and the cycle begins again.
In accordance with a second method of operation, the microplate transport is used to move microplates from the home location to the away location without returning them. The transport may be used to move one or two microplates per trip.
In accordance with a third method of operation, the microplate transport is used to move a microplate from the home location to the away location, wait for a pipetting function to be performed, then return the microplate to the home location. At the away location, the turntable may be turned to bring the microplate in closer proximity to the pipettor.
In a third aspect of the present invention, a microplate conveyor for moving microplates bi-directionally between, for example, the above-described storage and retrieval system and a workstation or between two workstations is provided. The conveyor, which is typically housed within the interior of the storage and retrieval system or workstation, is laterally extendable such that it may span a distance between two adjacent cabinets. A distance on the order of several inches or more may be spanned. The conveyor employs a fixed length, endless loop drive belt which is wound, in part, around tensioning elements that are capable of moving laterally as the conveyor is extended or retracted. The tensioning elements act to take up slack in the drive belt when the conveyor is retracted and to dispense slack when the conveyor is extended. A microplate holder which rides on the drive belt is capable of carrying up to four microplates at a time and may be loaded or unloaded by robotic equipment.